Jonathan DeHart, The Diplomat: Last Friday, millions of Buddhists across Asia gathered to celebrate a rather hazy date, but one with deep cultural import nonetheless: the so-called birthday of Siddhartha Gautama (better known as the Buddha). Depending on the country, the day is recognized as any time from the first full moon in May to April 8, the latter being steadily adhered to by the practical Japanese.

In reality, “Western scholars would tell you that we don’t even know the year in which the Buddha was born, much less the actual month and date,” José Ignacio Cabezón, professor of Tibetan Buddhism and Cultural…